The Fluid Mosaic Model of Cell Membrane is a widely accepted model for describing the structure of cell membranes. According to Fluid Mosaic Model, membranes are made up of a lipid bilayer that consists of two layers of phospholipid molecules. These molecules have a polar head group that is hydrophilic and oriented towards the extracellular side and the cytoplasmic side of the cell membrane. The polar head groups are separated by a hydrophobic core that is made up of the fatty acid tails of the phospholipids.
The lipid bilayer is extremely thin, with each layer measuring only 25 Å in thickness. The total thickness of the membrane is about 50 to 80 Å. This thinness is essential for the functioning of the cell membrane, as it allows small molecules to move easily through the membrane.
One of the most important characteristics of the lipid bilayer is its fluidity. The phospholipid molecules in the membrane can move laterally, allowing for the rapid diffusion of lipids and other membrane components. This free lateral movement of components is what gives the cell membrane its fluid nature.
The fluidity of the membrane is important for the movement of molecules across the membrane, as it allows them to pass through the membrane quickly and efficiently. Additionally, the fluidity of the membrane allows the membrane to change shape and to carry out a wide range of cellular functions.